A study published simultaneously with the Scripps team's paper by Professor Carlos Bustamante and colleagues from Stanford University also pointed to ancestry's importance, but this is the first time a team has been able to look at the problem on the whole-genome scale. "Others have indeed recognized ancestry as important," said Schork, "but no one had shown how much it could haunt a particular study, especially on a whole genome basis."
As importantly, prior to this study it wasn't clear how to address the ancestry issue. But the new study provides clear direction. The team calculated that identification of the vast majority of ancestral variants can be performed successfully with a reference panel of less than 20 genomesthough it could well take more to identify a particular ancestry group's rarest deviations. Of course, most people have more than one ancestry line, meaning that in practice a patient's reference panel would need to include multiple reference groups.
This result should act as a guide for continuing genomics work. Many ancestries are already well represented, meaning that assembling an effective reference panel is possible in some cases. But the number of whole genomes from a particular ancestral group isn't the only consideration. Ideally, reference genomes need to be from relatively disease-free people, meaning subjects who lived to an old age without major complications from genetic conditions.
Recognizing the importance of ancestral comparisons, researchers and companies can now deliberately work to fill any holes. "Building those sorts of
|Contact: Mika Ono|
Scripps Research Institute